90 TESTACEOUS MOLLUSCA. 



equilateral, rather rhombic, compressed, thin, yellowish white, dia- 

 phanous, umbones prominent, rather acute and tuberculose : liga- 

 ment inconspicuous. — Variety — Orbicular, less compressed, sub- 

 diaphanous and reddish brown. — Variety 2. — Orbicular, rhombic, 

 rather ventricose, sub-diaphanous and reddish : umbones less pro- 

 minent, blackish. \ . . \. — Europe. 



C. Obtusalis.* Lam. 6. — Del. t. 7. f. 2. — Pisidium D. 

 Pfeif. t. 5. /. 21, 2.— Gray. Turt. f. 149. Globose, obliquely 

 sub-ovate, slightly inequilateral, shining, very finely striated, green- 

 ish black, with a yellowish marginal zone, rarely altogether yellowish; 

 umbones rather prominent and very blunt. — Variety 1. — Ovate, 

 triangular, very ventricose, blackish or ochraceous, edge very blunt. 



■Sweden, fyc. 



C. Fontinalis. Lam. 7. Drap. t. 10. f. 8. to 11. — Pusil- 

 la.* Turt. M.f. 7. —Turt. B. p. 251. t. 11./. 16, 7. Orbicular, 

 ovate and rather compressed, very finely striated, and scarcely ine- 

 quilateral, umbones rather prominent. \. — France, Sweden, fyc. 



C. Australis. Lam. 8. Somewhat heart-shaped, tumid, 

 opaque, inequilateral, with transverse groove-like striae, umbones 

 prominent; beaks obliquely inclining. — Timor. -j-. — Variety — 

 Pellucid.— New Holland. 



G. Similis. Say. in Nich. Enc. Amer. 4. t. 1. f. 9. — Gould. 

 Mas./. 53. p. 73.— C. Sulcata. Lam. 9.— Del. t. 7. /. 3. 

 Sub -oval, sub -equilateral, marked with strongly raised lines of 

 growth, very convex, the sides nearly equally rounded, the anterior 

 slightly the larger and more pointed, the ventral edge very little 

 arcuated, remarkably broad across the beaks, which are but slightly 

 elevated, dark chesnut brown, inside bluish. The young thin and 

 compressed, hinge with minute very oblique cardinal teeth, the late- 

 ral distinct strong and white, the dorsal line nearly straight, and 

 the extremities truncated, so as to give the shell a quadrilateral 

 shape, light lemon or wax yellow. \ . . -^Q. — Massachusets, North 

 America. 



C. Striatina. Lam. 10. — Del. t. "/ \f. 4. Rounded, elliptic, 

 somewhat inequilateral, posteriorly shorter and slightly angulated, 

 greenish olive, convex, elegantly striated, beaks somewhat decorti- 

 cated. ^. — Lake George in North America. — Smaller and more 

 inequilateral than C. Cornea. 



C. Sarratoga. Lam. 11. — Del. t. 7. f. 9. Transversely 

 oval, posteriorly rounded and rather shorter, with an obtuse anterior 

 dorsal angle : a brownish epidermis and transverse striae : beaks 

 decorticated and eroded. 1. — Sarratoga in North America. 



C. Nitida.* — Pisidium. N. Jenyns Monocj. in Camb. Ph. 

 Tr. 4. j). lo. t. 20. f. 7, 8.— Gray. Turt. p. 283./. 150. 

 Rounded oval, slightly inequilateral, very shining, finely striated, 

 sides obtuse, ventral edge little arcuated, dorsal line scarcely slop- 



